SPECIAL PRINTING PROCESSES 469 



An alternative method of drying, which takes somewhat longer but gives better 

 results, is to squeegee the tissue on a ferrotype plate and to allow it to dry there 

 The ferrotype plate should first be thoroughly cleaned with water and a mild soap, 

 such as Castile, then dried, and powdered with talcum, which is well rubbed over the 

 surface and dusted off with a clean cloth. It should not be waxed in the usual manner 

 employed when squeegeeing glossy prints, for the carbon tissue may then refuse to 

 adhere to the transfer paper. Care should be taken to squeegee out all air bubbles 

 which may be trapped under the tissue, but the squeegeeing should not be heavy. 

 Drying may be hastened by the draft from an electric fan, and, when it is complete, 

 the tissue will snap off the ferrotype plate. This gives a more satisfactory working 

 surface than drying freely in the air. 



The squeegee used in this and subsequent operations should be of the scraper, not 

 the roller, type. An automobile windshield-wiper blade is too soft, and the ordinary 

 photographic scraper squeegee is too hard; a satisfactory article is that sold in hard- 

 ware and housefurnishing stores for cleaning windows. 



All squeegeeing should be done from the middle toward the ends of the print; 

 the squeegee must not be scrubbed back and forth. 



Printing. — The sensitiveness of the different tissues varies somewhat, the blacks 

 and blues printing in general a little faster than the browns and reds; further, the 

 sensitiveness varies to some extent with the moisture content, a tissue which is bone 

 dry printing faster than one which is not absolutely desiccated. In general, the Ivory 

 Black tissue, when fully dry, prints a trifle faster than a silver printing-out paper, so 

 if a print is made, proof deep, from the negative which is to be printed and the carbon 

 tissue is printed for three-quarters of the time required for this proof, the result will 

 be about right; further, there is considerable latitude in development, so the printing 

 need not be meticulously exact. 



Printing should preferably take place as soon as the tissue is dry, as the gelatin 

 tends to become insoluble even without exposure to light. If printing is to be post- 

 poned for any reason, the dry tissue should be stored in a lighttight receptacle which 

 contains also a small quantity of calcium chloride to keep the air dry; even with this 

 ]irecaution, the tissue will probably not remain in good condition for more than 2 or 

 3 days. 



When printing, it is necessary to have a "safe edge;" i.e., a border of at least J^ in. 

 and preferably 3^2 in. wide all around the tissue must be protected from light, or frilling 

 will take place during development. Therefore the tissue should be cut 1 in. larger 

 each way than the negative, which latter should be masked with opaque paper. 

 Also it is advisable to have a freshly cut edge on the tissue; hence this latter should be 

 trimmed to size immediately before printing. 



Transferring should take place immediately after printing, since with any bichro- 

 mated colloid there is a "continuing action," i.e., the printing, once started, takes place 

 even after the tissue is removed from the light. If for any reason transferring cannot 

 be done at once, this continuing action may be slightly retarded by keeping the print 

 under heavy pressure and may be entirely arrested by washing the print thoroughly in 

 cold water to remove the sensitizer. If this washing is done, the print may be dried 

 in the light and may then be transferred and developed at a future time, even weeks 

 later. 



Transferring. — The transfer paper should be soaked for a time in cold water to 

 soften the gelatin; with an ordinarily smooth paper, 15 min. will be enough, whereas a 

 very rough one may require }i hr. When both transfer paper and print are ready, 

 the latter is immersed, face up, in a tray of cold water and pressed down under the 

 surface. It will at first tend to curl up, face inward, gradually flattening out as it 

 absorbs water. Slightly before it is flat, it should be placed face to face with the 



